Embodiments according to the invention relate to wireless communication systems and particularly to a receiver and a method for decoding a receive signal in a wireless communication system.
One major goal for future wireless communication systems is a uniform user experience. In cellular systems cell-edge users suffer from path loss and interference from neighboring cells and experience a much lower data rate than users in the cell centre. In order to combat this problem, additional relay nodes can be used to support the communication. Up to now mainly two relaying functions are considered, namely Amplify-Forward (AF) and Decode-Forward (DF). DF can either mean a channel decoding at the relay or a hard decision directly on the received signal which will be called DetF here to avoid confusion. The latter case is interesting as the avoidance of computationally complex channel decoding would enable very simple and small relays with low power consumption. But both, AF and DetF have certain drawbacks leading to the idea to find more sophisticated solutions. AF suffers from noise amplification whereas with DetF useful information is lost due to the hard decision. For this purpose a relay function minimizing the mean squared error called Estimate-Forward (EF) has been proposed in the literature combining the benefits of AF and DF. The function for EF is the expectation value of the transmitted symbol and therefore combines the idea of exploiting the discrete alphabet with the aim of preserving reliability information about the first hop. In any case, it is desired to increase the user throughput.